Wireless receiving system for continuous waves



Dec. 21 ,1926. 1,611,848

E. H. ARMSTRONG WIRELESS RECEIVING SYSTEM FOR CONTINUOUS WAVES Original Filed Dec. 18, 1915 trains.

Patented Dec. 21, 1926.

- UNITED, STATES PATENT OFFICE.

EDWIN H. ARMSTRONG, OF NEW YOR K, N. Y., ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, OF EAST PORATION OF PENNSYLVANIA.

PITTSBURGH, PENNSYLVANIA, A- COR- WIRELESS RECEIVING SYSTEMzFOR CONTINUOUS WAVES.

Original application filed December 18, 1913, Serial No. 807,388. Divided and this application filed May 8, 1926. Serial No. 107,745.

The object of my invention is to provide improved wireless detecting or receiving means particularly suitable for continuous wave systems, that is, systems in which the sending station emits sustained waves as distinguished from a series of damped wave The present application is a division of my copending application filed December 18, 1913, Serial No. 807,388, for wireless receiving systems for continuous waves, In the present or divisional ap lication the claims are directed to so-calle heterodyne reception of signals, involving the use of a local source of continuous oscillations includirg an electron tube, such as an audion or cathode relay, and connections for pro ducin the oscillations by regeneration and at a lrequency different from that of the received signal waves. Claims directed to the roduction or generation of continuous oscillations with an electron tube by means of regeneration, without regard to any specific use of such oscillations, i. e., without regard to whether they are used for transmission or reception or other possible uses,

will be found in the arent application of which the present app ication is a division.

My invention involv es the use of a receiving and detecting system of coupled circuits in which oscillations are continuously maintained by an energy source, a battery, for example, supplying energy to the system through an electric valve in such manner as to make up the energy losses incident to such oscillations; said system of circuits includ ing acircuit having a natural period of oscillation differing slightly from the period of the received oscillations; together with connections whereby the combined received and local oscillations react upon the controlling valve to modify the-current through the valve and produce therein low frequency periodic variations audible in the telephone.

The herein described embodiment of my invention involves the use of a receiving system associated with the aerial substantially in the known manner, but made up of two coupled resonant circuits, the first of which, hereinafter referred to as the resonant receiving circuit, is coupled with the aerial in such a manner that oscillations are set up within it by the received waves; and

' operated by the oscillations in the receiving circuit and is in itself at the same time the receiving device or detector. I have had the best results by using as said valve a detector containing a path in which a stream of electrons is present, which path is so acted upon by the oscillations in the resonant receiving circuit as to vary the current in the detector circuit.

The drawing illustrates diagrammatically circuit connections suitable for carrying out my invention, though from the following description it will be understood that these circuit connections may be largely varied without departing from the spirit of the invention. in this diagram A is a conductor connected to the aerial and to the pri mary'P of an oscillation transformer, the secondary S of which is included in the resonant receiving circuit, which also includes an inductance L, a condenser C, a condenser C, the grid Gr and filament F of a so-called audion, and the telephones R shunted by the capacity C the circuit being completed from the telephones to the secondary S through a capacity C The second or detector circuit includes a plate or wing W and the filament F of the audion, the telephones R and the shunted condenser J2, a battery B shunted by condenser G a series condenser E shunted by a large inductance L to by-pass the direct current in the detector circuit, and" an inductance L. In this arrangement the condenser G which is common to the two high frequency circuits, constitutes an effective electro-static coupling between the two circuits supplementing the coupling of the audion and having the effect to facilitate the transfer of the energy of high frequency oscillations from the wing circuit' to the grid circuit. To those skilled in the art it will be understood that with such circuit connections a current in the receiving circuitiwill act on the valve to produce variations in the valve current of the same frequency and by reasonofthe circurrent is transferred from the detector or valve circuit to the receiving circuit to reinforce the current therein. In my United States Patent No. 1,113,149 of October 6, 19%. I have described a similar arrangement of circuit connections for receiving damped wave trains. In accordance with the resent invention, the adjustments are mac-e 1n the same general manner as described in the patent specification referred to, but the system is adjusted so that the valve supplies suflicient energy to the system to make np the energy losses therein, thereby causing the oscillations initiated in the system to persist instead-of dying out as they otherwise would.

So long as the oscillations thus generated in the system are of the same frequency asthe received oscillations no signals will be heard in the telephones, but by so tuning that circuit which determines the frequency of the local oscillations that the said local oscillations differ slightly in frequency from ,the frequency of the received oscillations,

the variations of potential at the grid due to the successive coincidence and opposition of Waves result in low frequency variations of the direct current in the detector circuit, and produce audible sound in the telephones. The frequency of these variations of direct current, and consequently the pitch of the note-in the'telephones, will depend upon the difference in frequency of the received oscillations and the local oscillations, as will be understood.

It will be understood that, notwithstanding the presence of the continuous local oscillations in the receiving system, the received oscillations are themselves reinforced by the high frequency currents which they set u in the wing circuit, in the manner explained in my patent referred to. In other words, the local oscillations combine with the received oscillations to produce beats, but do not interfere with the amplifying action which would occur if the local oscillations were not present.

As explained in my patent'above referred to, I have foundthat the effective charge upon the grid, and consequently the extent of variation of the current in the telephones, may be very greatly amplified by so connecting a condenser as C to the grid as to receive the charge which accumulates thereon, and by inserting in connections common to the coupled resonant circuits a relatively large inductance, that is, an inductance having a value of the order of one henry, for example, which may conveniently be the inductance of the telephones, as indicated on the diagram.

The organization is most effective when the electromagnetic coupling between the aerial and the resonant receiving circuit is extremely loose, the resonant receiving M K: -m=.02,

where M represents themutual inductance of the coupling and L and L, the inductance of the. primary and secondary, re

spectively. As a consequence of this loose coupling, the disturbing effects of atmospheric electricity are greatly reduced, and the ability of the receiving system to select only those particular waves to which it is attuned is increased. Inasmuch as the greater part of energy which causes the low frequency variations in the detector circuit is derived from the local battery, there is no difiiculty in creating in the detector circuit current variations sufiiciently powerful to give rise to easily audible sounds, even when the received oscillations represent but a minute quantity of energy.

It will be understood that the inductance of the telephones is made use of in that portion of the coupled circuits which is common to the two merely as a matter of convenience, and that the telephones may be located else-. where in the detector circuit if a suitable indu tance is included in the common path; and the circuit connections may be otherwise varied so long as the principles above described are observed.

Each of the inductances and capacities crossed by an arrow in the diagram is intended to be continuously adjustable, and I have found as a practical matter that the continuously adjustable series condenser C in the detector circuit affords convenient means for varying the frequency of the local oscillations, and consequently varying the number of beats and the pitch of the note in the telephone.

What I claim is-- 1. A wireless receiving system having a resonant receiving circuit upon which the received waves are impressed, coupled with a resonant detector circuit containing a source of sustained electrical oscillations, and means for causing the oscillations in the first named circuit to react upon the said source to vary the current in the detector circuit at an audible frequency. v

2. A wireless receiving system for sustained electrical oscillations having a resonant receiving circuit coupled with a resonant detector circuit containing a source of sustained oscillations and s0 tuned that the 1 oscillations generated therein differ slightly in frequency from the frequency of the received oscillations, and means for causing the oscillations in the first named circuit to react upon the said source to vary the current in the detector circuit.

3. A wireless receiving system for sustained electrical oscillations having a resonant receiving circuit attuned to the received oscillations and coupled with a resonant detector circuit containing a source of sustained oscillations and so tuned that the oscillations generated therein differ slightly in fre uency from the frequency of the received oscillations, and means for causing the oscillations in the first named circuit to react upon the said source to vary the current in the detector circuit.

4. A wireless receiving system having a resonant receiving circuit couped with a resonant detector circuit and connections common to the two circuits including an in ductance, a source of sustained elect'ricalos cillations in the detector circuit, and means including a capacity in the receiving circuit for causing the oscillations therein to react upon the said source to vary the current in the detector circuit.

5. A wireless receiving system having a resonant receiving circuit coupled with a resonant detector circuit, an audion having its wing connected to one terminal of the detector circuit, its grid connected to one terminal of the receiving circuit, and its filament common to both of said circuits, a source of energy in the detector circuit, the said circuits being so relatively tuned and coupled that energy from said source is transferred to the receiving circuit in sufiicient amount to maintain continuous oscillations, and an inductance in'the connections common to the two circuits.

6. In a wireless receiving system having a receiving circuit in which the received oscillations of radio frequency are combined with locally produced oscillations of radio frequency but differing slightly in frequency from the received oscillations to produce beats, an electric valve, and connections whereby the combined oscillations act upon saidvalve to create and to impress upon the receiving circuit similar but amplified 0scillations of radio frequency.

7. A wireless receiving system comprising a system of circuits, including a circuit hav"- ing a natural period of oscillation differing slightly from the period of received oscillations, and containing a source of energy, and an electric valve controlling the flow of the energy from said source into said circuit, and connections for applying the energy in said circuit to the actuation of the valve in sufficient amount to maintain continuous-oscillations.

8. In a wireless receiving system having a receiving circuit in which the receivedoscillations of radio frequency are combined with locally produced oscillations of radio frequency but differing slightly in frequency from the received oscillations to produce beats, an electric valve, connections whereby the combined oscillations act upon said valve to create and to impress upon the receiving circuit similar but amplified oscillations of radio frequency, and connections whereby the said amplified oscillations react upon the valve to produce large current variations of audible fre 'uency.

9. A wire ess receiving system comprising a system of circuits, including a circuit having a natural period of oscillation differing slightly from. the period of received oscillations, and containing a source of energy and an electric. valve controlling the flow of the energy from said source into said circuit to maintain continuous oscillations of said circuit, and connections for applying the received oscillations to the actuation of the valve to amplify said oscillations.

10,A wireless receiving system comprising a system of circuits, including a circuit having a natural period of oscillation ditl'ering slightly from the [period of received oscillations, and containing a source of energy and an electric valve controlling the flow of the energy from said source into said circuit. and connections for applying the energy in said circuit to the actuation of the valve in sutficient amount to maintain continuous oscillations and for simultaneously applying the received oscillations to the actuation of the lations.

11. A wireless receiving system comprising a system of circuits including a circuit having a natural period of oscillation differing slightly from the period of the received oscillations and containing a source of energy and an electric valve controlling the flow of energy from said source into said circuit to maintain continuous oscillation of said circuit at s natural period and connections for causing the combined incomvmg and local oscillations to react on the current through the valve to vary said current at an audible frequency.

.12. A wireless receiving system comprising a system of circuits including a circuit having a natural'period of oscillation differing slightly from the period of received oscillations and containing a source of energy and an electric valve controlling the flow of energy from said source into said circuit to maintain continuous oscillation in the system at the natural period of said circuit, and connections for applying the received oscillations to the actuation of the valve to produce in the system amplified oscillations of the received frequency and for causing the combined oscillations in the system to react on the current through the valve to vary said current at audible frequency.

13. An arrangement for receiving high frequency oscillations comprising an electric circuit, means for altering the received high valve to amplify said oscilill frequency current, a cathode relay for producing locally an alternating current of frequency different from that received, a grid included in said cathode relay, a circuit supplying the locally roduced alternating current to the grid 0 the relay, and an indicating instrument.

14. The method ofreceiving high frequency alternating current which comprises:

locally producing high frequency alternating current by causing current to flow in one of two coupled circuits and varying the flow of current in the first circuit by impressing the potential induced in the second circuit upon a conducting body interposed between two electrodes in the first circuit; controlling the frequency of the locally produced high frequency alternating current so as to cause it to differ from that of the received high frequency alternating current; combining said locally produced high frequency alternating current with the received high frequency alternating current; and converting the said combined high frequency alternating currents into a beat current having afre uency lower than that of the received high requency alternating current.

15. The method of receiving radio frequency alternating current which comprises selectively receiving the desired radio frequency alternating current, locally amplifyin at radio frequency the selected received ra i0 frequency alternating current; locally producing radio frequency alternating current by causing current to flow in one of two coupled circuits and varying the How of current in the first circuit by lmpressing the potential induced in the second circuit upon a conducting body interposed between two electrodes in the first circult; controlling the frequency of the locally produced radio frequency alternating current so as to cause it to differ from that of the selected received radio frequency alternating current; combining said locally produced radio frequency alternating current with the amplified received radio frequency alternating current; and converting the said combined radio frequency alternating currents :into

a beat current having a frequency lower than that of the received high frequency alternating current.

In testimony whereof I hereto afiix my signature.

EDWIN H. ARMSTRONG. 

